Pre-heat the oven to 200°C / 180°C fan assisted / gas mark 6 / 400°F.
Bring a large pan of salted water to the boil then add the pasta. Bring back to a boil then cook for 5 minutes. Drain and set aside.
Make a shallow cross at the base of each tomato then place in a large bowl and cover with just-boiled water. Allow to rest in the water for 5 minutes. Remove the tomatoes with a slotted spoon, peel off the skin (discard) and dice the tomato flesh. Set aside whilst you prepare the sauce.
Make the white sauce base by whisking the cornflour with the whole milk in a cold saucepan until smooth.
Add the black pepper, salt and nutmeg then place on the heat and bring up to a gentle simmer, whisking all the time to avoid lumps.
Turn the heat down to the lowest setting and tip in the tomatoes, mixing into the sauce.
Stir in half the cheddar (75g) and the cream cheese and keep stirring until melted.
Add the sundried tomato paste, garlic, dijon mustard, honey and chilli flakes and mix into the sauce until well combined. Keep at a low simmer for just a couple of minutes so the ingredients have time to get to know each other then turn off the heat.
Take a large mixing bowl and pour the sauce into it. Add the tuna, sweetcorn and parsley and mix together. Finally stir in the pasta until everything is well combined.
Pour the pasta and sauce into a large baking dish then sprinkle with the rest of the cheese and the breadcrumbs.
Bake for 25 minutes. Remove from the oven and allow to rest for 10 minutes before serving.